1. Field of the Invention
The present invention relates to a production installation for automatic assembly and testing of electronic card modules utilizing automatic program-controlled equipping, soldering and testing units, as well as a mechanical conveyor system, whereby a plurality of identical processing stations are respectively combined to form what are referred to as cells, whereby the control of the discrete parts such as, for example, printed circuitboards, components or mechanical parts, occurs by way of a master computer in cooperation with cell computers assigned to each cell and with the assistance of identifiers that can be applied to the discrete parts.
2. Description of the Prior Art
The reduction of inventories, increase of quality and avoidance of technically and dispositionally caused re-equipping or, respectively, wasting, is a significant contribution to increasing productivity. This is particularly true of the production of electronic systems which are fabricated upon assembly of high-quality components. The points of emphasis of such operations are the card module fabrication and testing.
Inventory costs are caused by run stocks (directly dependent on the throughput time) and module warehouse stocks of completely-tested card modules which cannot yet be called in by the following systems assembly because the type of structure is not yet complete. Reprocessing costs are reduced by the desired manufacturing quality of greater than 95% error-free card modules before the first test. Re-equipping and waste costs are caused by card modules which are no longer required after fabrication as a consequence of different disposition or, respectively, which are technically antiquated at the point in time they are needed. The risk is directly dependent on the overall running time.
It is known in the art to manufacture card modules in batches, whereby the reason for batching is that the equipping and testing machines must be specially equipped for the fabrication of a specific type of card module. Included in the set-up event is supplying the machines with material (components) and with the information sets which define the work sequence. Since the set-up time is currently relatively high in comparison to the actual manufacturing process, an attempt must be made to successively manufacture the greatest possible number of identical types of card modules after the exertion of a set-up time (batching). Card module production facilities which are known in the art manufacture the required spectrum of card module types and quantities in a cycle of, for example, a number of weeks, and output the quantity to a card module warehouse from which the following assembly works can selectively take the card modules. This buffer warehouse is necessary in order to keep enough items of a specific card module type on hand because this same type will not be manufactured again until after the time interval of a number of weeks.
The batches combine the requirements of a period of the systems assembly (for example, month). The production and test facilities must be newly established for each batch. A batch is only forwarded to the following production step when the last unit is processed. The combination of card modules of the same type is a compulsory necessity in order to maintain the set-up time in a justifiable relationship to the production time. All known activities attempt a gradual improvement of the current condition without departing from the basic condition of batching. A throughput time on the order of magnitude of, for example, two weeks for the card module fabrication (from calling in the material up to the finished electrical test) seems to be a natural lower limit. However, this value can only be achieved when the batch size is reduced down to the limit at which the set-up expense becomes no longer economically justifiable due to its exponential increase (batch sizes of 15-20 items).
The German patent application No. P 34 18 210, as well as European patent application No. 85105522.8 (publication No. 164,563-A1; Dec. 18,1985 ) discloses a method for set-up free fabrication of card modules without the necessity of batching wherein the production process is largely automated. The components required for assembly (equipping and soldering), on the one hand, and the information sets both for the assembly and for the testing of individual card module units are situated in random access of the assembly and testing station. The assembly and testing stations themselves are computer-guided facilities, whereby the transport of the products from station-to-station is additionally guided by further computers (cell computers) and the overall production process, beginning from the input of the printed circuitboard up to the delivery of the completely-equipped, tested card module to the further processing department is coordinated by a master computer, which is again overlaid on the self computer.